1. Field of the Invention
The present invention relates generally to a pressurized liquid, load-bearing structure. More particularly, the present invention relates to column with a longitudinally expandable sleeve to contain a pressurized liquid.
2. Related Art
In mining it is often necessary to support the ceilings of tunnels and cavities to resist collapse. Various different methods have been proposed to prevent ceiling collapse. Traditional methods include wood or steel structures forming a framework to support the ceiling. Such wood or steel structures often become permanent due to the difficulty of removing them. In addition, the transportation of the necessary materials into the mine, and the construction of the framework, is often difficult and time consuming. Cement structures also have been proposed, but are difficult to use because the concrete must cure before accepting loads. In addition, unexpected loads can crush and destroy the forms before the concrete cures.
It has been recognized that it would be advantageous to develop an improved method and apparatus for supporting loads, such as ceilings in a mine. In addition, it has been recognized that it would be advantageous to develop an expandable and/or collapsible load bearing structure capable of being collapsible for transportation, and expandable for use.
The invention provides a load-bearing, pressurized-fluid column apparatus for supporting a load with respect to a support surface. An elongated, flexible sleeve retains a substantially incompressible liquid. The elongated, flexible sleeve has at least two configurations, including a collapsed and an expanded or rigid configuration. In the collapsed configuration, the sleeve is not filled, and has a first, shorter length. In the expanded or rigid configuration, the sleeve is filled with the liquid, and has a second, longer length sized to extend to and between the load and the support surface. The incompressible liquid is capable of transferring a compressive force of the load to tension load in the sleeve. A valve allows the liquid to be added to the sleeve, and prevents escape of the liquid.
In accordance with a more detailed aspect of the present invention, the sleeve can include a flexible, high strength woven fabric to withstand high-tension loads, and a flexible, liquid impervious layer to contain liquid.
In accordance with another more detailed aspect of the present invention, the sleeve has a circular, cylindrical shape in the expanded configuration to withstand tension loads.
In accordance with another more detailed aspect of the present invention, the apparatus further includes a base to abut the support surface, and a cap to abut the load. The sleeve has opposite ends, one end being coupled to the base and the other end being coupled to the cap to form an enclosure to extend to and between the load and the support surface in the expanded configuration.
In accordance with another more detailed aspect of the present invention, at least one of the ends of the sleeves is adjustably coupled to either the cap or the base to selectively adjust the length of the sleeve, and the distance between the cap and the base. A ring can be securable to either the cap or the base. One end of the sleeve can be wrapped around the ring and selectively slid around the ring to adjust the length of the sleeve, and the distance between the cap and the base.
In accordance with another more detailed aspect of the present invention, the apparatus can further include means for limiting longitudinal extension of the sleeve. For example, cables or rods extending between the base and the cap can be used.
A method for utilizing the column apparatus for supporting a load with respect to a support surface includes positioning a flexible sleeve in a desired location between the load and the support surface. A substantially incompressible liquid is introduced into the sleeve to lengthen the sleeve to a length extending to and between the load and the support surface. Escape of the liquid from the sleeve is prevented so that the volume of the sleeve between the load and the support surface is maintained at a substantially constant value so as to resist movement of the load towards the support surface.
In accordance with another more detailed aspect of the present invention, the liquid in the sleeve can be pressurized.
In accordance with another more detailed aspect of the present invention, the step of introducing a liquid into the sleeve further includes opening a valve. Likewise, the step of preventing escape of the liquid includes closing the valve.
In accordance with another more detailed aspect of the present invention, the step of positioning a sleeve further includes positioning a first plate to abut the support surface. A first end of the sleeve is secured to the first plate so that the first plate seals the first end of the sleeve. A second end of the sleeve is secured to a second plate so that the second plate seals the second end of the sleeve. The second plate is positioned to abut the load.
In accordance with another more detailed aspect of the present invention, the length of the sleeve is adjusted to extend to and between the load and the support surface. An end of the sleeve can be wrapped around a ring.